Marshal vs the Assassins. Sir William the Marshal, legend in his own time, has promised to go on crusade, a vow made to his Young King as he lay dying. But when the Oliphant, legendary war horn of Roland, is stolen by the lethal Assassins, he’s charged with returning the relic in order to stop the very thing he’d vowed to undertake—a crusade; this one engineered by the thieves.